The transformation of America’s environmental movement began, as ex-United Steelworkers board member David Foster recalls, in late 2004 in a borrowed conference room at a table surrounded by union officials, top aides and the always-present group of Washington assistants.

About the same time, another group of environmentalists began networking with equally unlikely partners.

Jonathan Lash, president of the World Resources Institute, asked General Electric CEO Jeff Immelt to help lobby for a national climate policy. The dialogue they launched eventually became the basis of legislation now in Congress to cap greenhouse gas emissions.

“We had been lobbying for what we felt was right but not seeing the interconnectedness,” Foster said of the different efforts and their unusual coalitions.

Today, alliances between Big Business, labor and environmental groups — once nearly impossible to imagine — are not only restructuring political advocacy but also shaping policy in President Barack Obama’s Washington.

Labor unions, Fortune 500 corporations, utility companies and other corporate interests have joined forces with environmentalists in at least five different lobbying coalitions. The labor-environmentalist pact eventually became the Blue-Green Alliance, a strategic partnership of six unions, NRDC and the Sierra Club. And the meetings between Immelt and Lash grew into the United States Climate Action Partnership, an association of 26 utilities, manufacturers and technology companies and five environmental organizations.

All of the groups are focused on a very big goal: a cap-and-trade system that will curb greenhouse gas emissions across the economy.

“We are talking about transforming the energy economy of the country and the world,” said Beinecke. “Our aim is to have the biggest tent possible, taking into account what the concerns are — from business to labor to the environmental community — and crafting something that can get the broader support.”

The alliances are particularly remarkable because in the past, environmentalists had frequently battled with both labor and business over conservation efforts, new environmental standards and cleanups.

“It was a fairly ‘out there’ decision,” Beinecke said of forging the alliances, “because you were going in not knowing what you were going to come out with.”

But lawmakers say the work done by the coalitions — particularly USCAP — gave the climate bill momentum to move though the House less than six months after the Obama administration took office.

The first hearing held on the legislation by the House Energy and Commerce Committee in January featured testimony from nine CEOs of USCAP companies.

“Their testimony made it clear that private legislation would not hurt their companies, would not hurt job creation and would not hurt our economy, and that was a very important component to our ability to be successful in passing [legislation] in June,” said Rep. Ed Markey (D-Mass.), a main sponsor of the bill.

The alliances are strong, but they don’t have a monopoly on the climate debate. A long list of coal companies, oil refiners and other fossil-fuel-intensive industries vocally oppose the legislation. Many labor unions have serious concerns about international competition moving energy jobs overseas. And the Chamber of Commerce, the country’s most powerful business organization, remains deeply skeptical of a cap-and-trade system.

“I still get challenged every day from industry colleagues and others who ask, ‘Why are you in this conversation and having this kind of discussion?’” said Shell Oil CEO Marvin Odum, a member of USCAP. There are signs, however, that the alliances are reshaping traditional Washington fault lines. Last fall, a series of companies left the Chamber of Commerce over disagreements with the group’s stance on climate legislation.

Chamber President Tom Donohue blamed the resignations on an “orchestrated pressure campaign” by environmental activists.

Environmental groups dismissed Donohue’s charge, saying that the companies decided to leave the group entirely on their own. But even the idea that green concerns could cause big Fortune 500 companies such as Apple and PG&E to quit a prominent business association was a sign that the environmental movement had regained some of its political power.

As recently as 2004, a paper titled “The Death of Environmentalism” sparked a period of fierce self-reflection among environmentalists. The controversial essay was published at a particularly low moment for the green movement, which had watched defeats roll in during the Bush administration.

Authors Michael Shellenberger and Ted Nordhaus accused environmental groups of squandering their power, failing to build the popular inspiration and political coalitions necessary to pass groundbreaking environmental legislation.

“By thinking only of their own narrowly defined interests, environmental groups don’t concern themselves with the needs of either unions or the industry,” they wrote. “As a consequence, we miss major opportunities for alliance building.”

The decision to start building new types of coalitions came as business and labor were undergoing their own re-evaluations.

Labor also had suffered under the Bush administration, particularly as economic equity issues slid down the agenda after the Sept. 11 attacks. That followed eight years of the Clinton administration, when union leaders watched a Democratic president push policies to expand overseas trade — often, they felt, at the expense of American workers.

“The 2004 elections made it clear that unless progressives could project a positive vision of where we could take the global economy, that it would be very, very hard for us to capture the attention of the American public,” said Foster, now executive director of the Blue-Green Alliance. “We needed to have some kind of global green New Deal.”

As liberals worked to join forces, businesses were slowly beginning to realize that sustainable practices could lead to cost savings and profits. Wal-Mart, Dupont and a handful of other major corporations began investigating ways to reduce packaging, increase energy efficiency and invest in new, green technologies.

The rest of the business world — from financial services corporations to insurance companies — began to catch on, said Mindy Lubber, president of Ceres, a national network of investors, environmental organizations and public interest groups.

“Ceres had been talking about sustainability as a capital markets issue for 20 years, and probably 17 years of those years it was a debate,” Lubber said. “We are no longer debating that thesis; it’s much more a question of how quickly companies are working to integrate their sustainability into their business plans.”

Meanwhile, top corporate officials “were all passing each other in and out of congressional offices and otherwise giving our own messages,” said Odum, so a small group of 10 businesses began meeting together as USCAP. “It was just the perfect opportunity to get everyone together.”

The group had some internal differences. The environmentalists wanted stricter short-term emissions reductions, while businesses wanted to set lower goals initially so they could have more time to develop new technologies. But in 2007, the organization released a set of principles to address global warming. Two years later, they came out with specific policy recommendations for Congress.

Some of the same environmental groups involved with USCAP also began reaching out to labor.

In 2004, the NRDC, the Sierra Club and the Union of Concerned Scientists held a one-day strategic retreat with USW. After a series of meetings, the groups decided to join forces in a new organization.

A partnership between the steelworkers and the Sierra Club might seem peculiar, but they had institutional similarities that made it a good fit. Both were membership organizations with local chapters that could work to build support in communities across the country.

The partnership became known as the Blue-Green Alliance. After two years of testing, it opened up its doors to five additional union partners and expanded its agenda beyond environmental work. This past fall, environmental groups helped push for the Employee Free Choice Act, legislation that would make it easier for labor to unionize.

“There might be a mine permit issue in the Southwest or a timber harvesting plan in Montana that we disagree on,” said Foster. “But those differences are so small compared to what we agree on, that issues like that just never get out of control anymore.”